Iron-nickel-based electromagnetic shielding material for vehicle and preparation method of iron-nickel-based electromagnetic shielding material

Abstract

The invention discloses an automotive iron-nickel-based electromagnetic shielding material and a preparation method thereof, and relates to the technical field of electromagnetic shielding of new energy automobiles. The iron-nickel-based electromagnetic shielding material for the vehicle comprises the following raw materials in parts by weight: 30-50 parts of modified iron-nickel-based alloy powder, 40-60 parts of polyurethane resin, 5-15 parts of modified polyethylene glycol terephthalate short fibers, 2-8 parts of nano-zinc oxide, 3-10 parts of linen fibers, 1-3 parts of a silane coupling agent KH550, 2-5 parts of a foaming agent, 0.3-0.8 part of 2, 3, 5-trimethyl-1, 3-pentanediol monoisobutyrate, 1-3 parts of a coupling agent KH550, 1-3 parts of a coupling agent KH550 and 1-3 parts of a coupling agent KH550. And 0.5-2 parts of sodium polycarboxylate, and a sufficient amount of electromagnetic shielding non-woven fabric. According to the material, full-band electromagnetic shielding is achieved through the synergistic effect of the modified iron-nickel-based alloy powder and the electromagnetic shielding non-woven fabric. Multiple modified raw materials and an optimized process are selected, light weight and excellent shielding performance are considered, the requirements of new energy automobiles are met, and the application value is high.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology for new energy vehicles, specifically to an iron-nickel-based electromagnetic shielding material for vehicles and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the integration of automotive electronic equipment is constantly increasing. The electromagnetic radiation generated by various high-frequency communication and power control systems is becoming increasingly complex. Electromagnetic interference has become a key issue affecting vehicle driving safety, electronic equipment stability, and the health of drivers and passengers. As a core component for solving this problem, the performance of electromagnetic shielding materials directly determines the electromagnetic compatibility level of a vehicle.

[0003] Currently, automotive electromagnetic shielding materials mainly rely on traditional materials such as metal mesh and metal fabrics. While these materials can achieve a certain shielding effect in the mid-to-high frequency bands, they have significant drawbacks. On the one hand, the high density of metal materials increases the vehicle's weight, which contradicts the trend of lightweight development in new energy vehicles and affects the vehicle's range. On the other hand, traditional metal shielding materials are insufficient in shielding low-frequency electromagnetic radiation and cannot cover the wide-band electromagnetic interference generated by the power system and battery management system of new energy vehicles, resulting in incomplete shielding across the entire frequency range.

[0004] Meanwhile, some existing shielding materials are prepared using single materials or simple composite processes, resulting in problems such as poor interfacial bonding, insufficient mechanical properties, and susceptibility to corrosion and aging. Their shielding performance deteriorates significantly after long-term use, failing to meet the long-term performance requirements of vehicles under complex operating conditions. Furthermore, traditional manufacturing processes are often cumbersome, energy-intensive, and difficult to recycle, failing to meet the requirements of green and environmentally friendly industrial development.

[0005] To meet the core requirements of full-band electromagnetic shielding, lightweighting, and high stability for new energy vehicles, it is urgent to develop a new type of electromagnetic shielding material that combines wide-band shielding effectiveness, lightweight structure, and excellent mechanical properties. This will address the prominent shortcomings of existing materials in terms of frequency coverage, weight control, and durability, and promote the upgrading and iteration of automotive electromagnetic shielding technology. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an iron-nickel-based electromagnetic shielding material for automobiles and its preparation method, solving the problems of narrow shielding frequency band, heavy weight, poor mechanical properties, easy aging, complicated process and high energy consumption of existing automotive electromagnetic shielding materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A nickel-iron-based electromagnetic shielding material for automobiles comprises the following raw materials in parts by weight: 30-50 parts modified nickel-iron-based alloy powder, 40-60 parts polyurethane resin, 5-15 parts modified polyethylene terephthalate short fiber, 2-8 parts nano zinc oxide, 3-10 parts flax fiber, 1-3 parts silane coupling agent KH550, 2-5 parts foaming agent, 0.3-0.8 parts 2,6-di-tert-butyl-p-cresol, 0.5-2 parts sodium polycarboxylate, and sufficient electromagnetic shielding nonwoven fabric.

[0009] Furthermore, the flax fiber undergoes alkali treatment, specifically as follows: 100g of flax fiber is added to 500ml of 5wt.% sodium hydroxide solution, stirred at 80℃ for 2 hours, washed until neutral, and then dried at 100℃ for 3 hours. Alkali treatment at 80℃ removes impurities and lignin from the surface of the flax fiber, activates surface groups, and enhances the bonding strength with the resin matrix; washing until neutral prevents residual alkali from corroding other components; and drying at 100℃ ensures stable fiber moisture content, ultimately enhancing the material's mechanical stability and structural integrity.

[0010] Furthermore, the electromagnetic shielding nonwoven fabric has a silver fiber content of ≥15%, ensuring shielding effectiveness in the mid-to-high frequency bands, and a surface density of 80-120 g / m². 2 It balances shielding performance with lightweight requirements, avoiding both excessively low areal density leading to weak shielding and excessively high material weight, thus meeting the dual needs of weight reduction and protection for new energy vehicles.

[0011] Furthermore, the foaming agent is a compound of sodium bicarbonate and citric acid in a mass ratio of 1.3:1, which makes the reaction rate of sodium bicarbonate and citric acid easier to control. When heated, it releases uniform bubbles in a synergistic manner to form a dense porous structure. While reducing the material density to achieve lightweighting, it does not damage the shielding and mechanical properties, and avoids the problems of uneven bubbles or violent reactions caused by a single foaming agent.

[0012] Furthermore, the modified iron-nickel-based alloy powder is prepared using the following specific steps:

[0013] A1. Take iron-nickel-based alloy powder, add deionized water, stir to disperse and form a suspension, adjust the pH value to 5-6 with 1 mol / L dilute hydrochloric acid; slowly add tetrabutyl titanate and ethanol at the same time, stir at 50-60℃ for 2-3 hours; continue to add silane coupling agent KH550 to the system, raise the temperature to 70-80℃, stir and react for 1.5-2 hours; after the reaction is completed, filter and wash until neutral, dry at 100℃ for 5 hours to obtain the first modified iron-nickel-based alloy powder; through the hydrolysis coating of tetrabutyl titanate and the silanization treatment of KH-550, a dense TiO2 protective layer is formed and amino active sites are introduced, which not only inhibits the oxidation of powder, but also provides a stable binding basis for subsequent modification.

[0014] A2. Take the first modified iron-nickel-based alloy powder, add carboxylated multi-walled carbon nanotube aqueous dispersion, and ultrasonically disperse for 40 min; prepare an iron-nickel chloride mixed solution, slowly add it dropwise to the above system, heat to 80-90℃, add citric acid as a complexing agent, stir for 10 min, and then add 1 mol / L sodium hydroxide solution to adjust the pH to 8-9; transfer the mixed system to a hydrothermal reactor and crystallize at 110-120℃ for 1.5-2.5 h; after cooling to room temperature, magnetically agglomerate it for 10 min under the action of an electromagnet with a magnetic field strength ≥0.8T, then decant the supernatant, collect the magnetic agglomeration product, wash it with deionized water until the filtrate is neutral, and vacuum dry at 100℃ for 4 h to obtain the second modified iron-nickel-based alloy powder; construct a three-dimensional conductive-magnetic synergistic network of "carbon nanotube-ferrite" by means of carbon nanotube adsorption and hydrothermal synthesis of NiFe2O4 ferrite, synergistically improve magnetic loss and electrical loss capability, and broaden the shielding frequency band.

[0015] A3. Take the second modified iron-nickel-based alloy powder, add N,N-dimethylformamide, and ultrasonically disperse for 30 min; add silane coupling agent KH570, heat to 70-80℃, and stir under nitrogen protection for 1.5-2 h; then add glycidyl methacrylate and benzoyl peroxide, heat to 85-90℃, and react for 2.5-3 h; centrifuge to separate the product, wash three times with anhydrous ethanol to remove unreacted monomers and initiator residues, and dry at 130℃ for 5 h to obtain the modified iron-nickel-based alloy powder. Grafting with silane coupling agent KH570 and polymerization with glycidyl methacrylate introduces epoxy groups, achieving chemical bridging between the powder and the matrix and fibers, strengthening interfacial bonding, and improving the material's structural stability and shielding effectiveness uniformity.

[0016] Furthermore, the ratio of iron-nickel-based alloy powder, deionized water, tetrabutyl titanate, ethanol, and silane coupling agent KH550 in A1 is 100g: 400-500ml: 20-30ml: 100-150ml: 3-5g; the iron-nickel-based alloy powder has a nickel content of 70-80%, an iron content of 20-30%, and a particle size of 5-20μm.

[0017] Furthermore, in A2, the ratio of the first modified iron-nickel-based alloy powder, the carboxylated multi-walled carbon nanotube aqueous dispersion, the iron-nickel chloride mixed solution, and citric acid is 100g:200-300ml:50-70ml:4-6g; wherein, the carboxylated multi-walled carbon nanotube aqueous dispersion has a solid content of 1.5wt.% and a pH of 3-4; the iron-nickel chloride mixed solution is FeCl₂. 3• 6H2O and NiCl 2• Mixed with 6H2O, in which Fe 3+ :Ni 2+ The molar ratio was 2:1, and the total concentration was 0.8 mol / L.

[0018] Furthermore, the ratio of the second modified iron-nickel-based alloy powder, N,N-dimethylformamide, silane coupling agent KH570, glycidyl methacrylate, and benzoyl peroxide in A3 is 100g:300-400ml:7-9ml:12-16ml:0.7-0.9g.

[0019] Furthermore, the modified polyethylene terephthalate short fibers are prepared using the following specific steps:

[0020] B1. Take polyethylene terephthalate short fibers, add 5 wt.% sodium hydroxide solution, and stir at 80-90℃ for 2-3 hours; wash repeatedly with deionized water until the pH of the washing solution is 7, add 1.5 mol / L hydrochloric acid solution, and soak at room temperature for 30 minutes; wash the product until neutral, and dry at 100℃ for 4 hours to obtain the first modified polyethylene terephthalate short fibers; through alkaline hydrolysis and neutralization with hydrochloric acid, hydroxyl groups are generated on the fiber surface and a rough structure is formed, which improves the physical adsorption capacity and the activity of subsequent modification reactions.

[0021] B2. Take the first-modified polyethylene terephthalate short fibers, add deionized water, and ultrasonically disperse for 20 min. Adjust the pH value to 4-5 with a 0.2 mol / L acetate-sodium acetate buffer solution. Slowly add silane coupling agent KH550 and ethanol at the same time, and stir the reaction at 60-70℃ for 1.5-2 h. After the reaction is completed, filter and wash with water, and dry at 80℃ for 2 h to obtain the second-modified polyethylene terephthalate short fibers. The KH550 silanization treatment introduces amino active sites on the fiber surface, which can form chemical bonds with the polyurethane resin matrix, significantly improving the interfacial bonding force between the fiber and the matrix.

[0022] B3. Take the second batch of modified polyethylene terephthalate (PET) short fibers, add 0.5 mol / L hydrochloric acid solution, and soak for 30 min; slowly add aniline monomer, stir and adsorb at room temperature for 1 h, then add 1.2 mol / L ammonium persulfate solution, and stir and react at 10-15℃ for 2-3 h; after completion, filter and wash with water until no chloride ion residue remains; add the product to a pre-prepared dopamine solution, heat to 40-50℃ and stir and react for 1-1.5 h; after completion, filter and wash with water, and vacuum dry the product at 80℃ for 5 h to obtain modified PET short fibers. A polyaniline conductive layer is formed through in-situ polymerization of aniline. After washing away residual oxidant, the active sites are retained by in-situ oxidative polymerization of polydopamine, giving the fibers conductive function. Simultaneously, an interfacial synergistic reaction with iron-nickel-based powder is achieved, enhancing the shielding synergistic effect.

[0023] Furthermore, the ratio of polyethylene terephthalate short fibers, sodium hydroxide solution, and hydrochloric acid solution in B1 is 100g: 500-600ml: 10-15ml.

[0024] Furthermore, the ratio of the first modified polyethylene terephthalate short fiber, deionized water, silane coupling agent KH550, and ethanol in B2 is 100g: 300-400ml: 8-12ml: 60-70ml.

[0025] Furthermore, the ratio of the amount of the second modified polyethylene terephthalate short fiber, hydrochloric acid solution, aniline monomer, ammonium persulfate solution, and dopamine solution in B3 is 100g: 200-300ml: 10-15ml: 50-70ml: 200-300ml; the dopamine solution contains dopamine hydrochloride at a concentration of 5g / L, and the solvent is a Tris-HCl buffer solution with a pH of 8.0.

[0026] A method for preparing an iron-nickel-based electromagnetic shielding material for automobiles, specifically comprising the following steps:

[0027] S1. Add 40-60 parts of polyurethane resin to the reactor, heat to 60-70℃, stir at 300-400 r / min, and keep warm for 30 min to melt the resin and make it form a uniform flow state; add 0.3-0.8 parts of 2,6-di-tert-butyl-p-cresol and 0.5-2 parts of sodium polycarboxylate, and continue stirring for 15-20 min to obtain the pretreated resin matrix;

[0028] S2. Add 30-50 parts of modified iron-nickel based alloy powder, 2-8 parts of nano zinc oxide, and 3-10 parts of flax fiber to a high-speed mixer at a speed of 800-1000 r / min for 15-20 min; then add the pretreated resin matrix, adjust the speed to 500-600 r / min, and mix for 30-40 min to form a stable composite powder system.

[0029] S3. Add 5-15 parts of modified polyethylene terephthalate short fibers to the above composite powder system, add 1-3 parts of silane coupling agent KH550, heat to 80-90℃, stir at 400-500 r / min, and mix for 25-35 min; then add 2-5 parts of foaming agent to the mixture, adjust the temperature to 70-80℃, stir at 300-400 r / min, and stir for 15-20 min to obtain the foaming precursor material;

[0030] S4. Preheat the mold to 100-110℃ and adjust the mold pressure to 5-8MPa, then keep it warm for later use. Preheat the mold with the above-mentioned foaming precursor material, and lay it out with a thickness of 1.2-1.5 times the target finished product thickness. Then, lay the electromagnetic shielding non-woven fabric on the upper and lower surfaces of the material, and after closing the mold, maintain a pressure of 5-8MPa for hot pressing and fusion. Maintain 100-110℃ and 5-8MPa pressure for 20-30 minutes to ensure that the foaming is completely bonded to the interface. After slowly depressurizing to normal pressure, continue to keep it warm for 10-15 minutes to eliminate internal stress and avoid deformation of the finished product.

[0031] S5. Remove the molded composite material and cure it again in a 120-130℃ forced-air drying oven for 2-3 hours. After naturally cooling to room temperature, trim and trim the edges according to the dimensions of the target installation part to obtain the automotive iron-nickel-based electromagnetic shielding material.

[0032] This invention provides an iron-nickel-based electromagnetic shielding material for automobiles and its preparation method, which has the following beneficial effects:

[0033] 1. This invention achieves high-efficiency electromagnetic shielding across the entire frequency band, overcoming the limitations of traditional shielding materials. Through the synergistic effect of modified iron-nickel-based alloy powder and electromagnetic shielding nonwoven fabric, the modified iron-nickel-based alloy, with its excellent magnetic permeability, effectively blocks low-frequency electromagnetic radiation, while the electromagnetic shielding nonwoven fabric precisely shields mid-to-high-frequency electromagnetic waves. The combination of these two materials achieves full-frequency coverage from low to mid-to-high frequencies, completely overcoming the limitation of traditional metal mesh and metal fabrics that can only shield mid-to-high frequencies. This effectively resists complex electromagnetic interference generated by the power systems and electronic devices of new energy vehicles, ensuring the stability of vehicle electronic equipment and the health of passengers. Simultaneously, the synergistic optimization of the multi-component structure improves the uniformity of shielding effectiveness, avoiding localized weak shielding and adapting to the diverse electromagnetic protection needs of new energy vehicles.

[0034] 2. Significant advantages in lightweight materials, aligning with the energy-saving and emission-reduction trend of new energy vehicles. This invention abandons traditional heavy metal shielding materials, using polyurethane resin and other polymer foam substrates as carriers, combined with lightweight electromagnetic shielding non-woven fabric and modified short fibers, significantly reducing material density while ensuring shielding performance. Compared to traditional metal-based shielding materials, the finished product is lighter, and through reasonable component ratios and foaming processes, it maintains structural integrity while achieving lightweighting, with no significant strength loss. The lightweight design directly reduces vehicle weight, decreases vehicle energy consumption, and improves the range of new energy vehicles. It also facilitates installation and disassembly, reducing vehicle assembly and maintenance costs, conforming to the automotive industry's development direction of lightweighting and efficiency.

[0035] 3. The material exhibits outstanding comprehensive mechanical properties and durability, making it suitable for complex vehicle operating conditions. Through multiple modification treatments of the iron-nickel-based alloy powder and polyethylene terephthalate short fibers, as well as alkali treatment optimization of flax fibers, the interfacial bonding force between each component and the resin matrix is ​​significantly improved, forming a structurally stable composite system. The finished product possesses excellent tensile strength, flexibility, and anti-aging properties. Simultaneously, the addition of antioxidants such as 2,6-di-tert-butyl-p-cresol effectively slows down the aging process, extends service life, and meets the stringent environmental requirements of long-term outdoor use and complex road conditions in new energy vehicles, reducing the frequency of replacement and operating costs.

[0036] 4. The preparation process is scientific, environmentally friendly, and highly controllable, possessing the potential for large-scale production. The preparation process of this invention requires no complex or specialized equipment; the process parameters for each step are clearly defined, facilitating precise control and ensuring product quality stability. The raw materials used avoid high-pollution and high-energy-consuming components, and there are no emissions of toxic or harmful substances during production, complying with green and environmentally friendly industrial policies. Furthermore, the process steps are seamlessly connected, and the modification and composite molding processes are highly efficient. Compared to the complex processing of traditional shielding materials, energy consumption is reduced by more than 20%, significantly improving production efficiency. In addition, the raw materials are widely available and cost-controllable, and the component ratios are flexibly adjustable, allowing for customized production based on the shielding requirements and installation scenarios of different vehicle models. This adapts to the diverse production needs of new energy vehicles and has broad market application prospects. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1: Preparation of automotive iron-nickel-based electromagnetic shielding material. The specific preparation steps are as follows:

[0039] S1. Add 40 parts of polyurethane resin to the reactor, heat to 60℃, stir at 300 r / min, and keep warm and melt for 30 min to make the resin form a uniform flow state; add 0.3 parts of 2,6-di-tert-butyl-p-cresol and 0.5 parts of sodium polycarboxylate, and continue stirring for 15 min to obtain the pretreated resin matrix.

[0040] S2. Add 30 parts of modified iron-nickel-based alloy powder, 2 parts of nano zinc oxide, and 3 parts of flax fiber to a high-speed mixer and mix at 800 r / min for 15 min. Then add the pretreated resin matrix, adjust the speed to 500 r / min, and mix for 30 min to form a stable composite powder system.

[0041] S3. Add 5 parts of modified polyethylene terephthalate short fibers to the above composite powder system, add 1 part of silane coupling agent KH550, heat to 80℃, stir at 400 r / min, and mix for 25 min; then add 2 parts of foaming agent to the mixture, adjust the temperature to 70℃, stir at 300 r / min, and stir for 15 min to obtain the foaming precursor material;

[0042] S4. Preheat the mold to 100℃ and adjust the mold pressure to 5MPa, then keep it warm for later use. Preheat the mold with the above-mentioned foaming precursor material, and lay it out with a thickness of 1.2 times the target finished product thickness. Then lay the electromagnetic shielding non-woven fabric on the upper and lower surfaces of the material, close the mold, and maintain a pressure of 5MPa for hot pressing and fusion. Maintain 100℃ and 5MPa pressure for 20 minutes to ensure that the foaming is completely bonded to the interface. After slowly depressurizing to normal pressure, continue to keep it warm for 10 minutes to eliminate internal stress and avoid deformation of the finished product.

[0043] S5. Remove the molded composite material and cure it again in a 120℃ forced-air drying oven for 2 hours. After naturally cooling to room temperature, trim and trim the edges according to the dimensions of the target installation part to obtain the automotive iron-nickel-based electromagnetic shielding material.

[0044] Example 2: Preparation of automotive iron-nickel-based electromagnetic shielding material. The specific preparation steps are as follows:

[0045] S1. Add 60 parts of polyurethane resin to the reactor, heat to 70℃, stir at 400 r / min, and keep warm and melt for 30 min to make the resin form a uniform flow state; add 0.8 parts of 2,6-di-tert-butyl-p-cresol and 2 parts of sodium polycarboxylate, and continue stirring for 20 min to obtain the pretreated resin matrix.

[0046] S2. Add 50 parts of modified iron-nickel-based alloy powder, 8 parts of nano zinc oxide, and 10 parts of flax fiber to a high-speed mixer at a speed of 1000 r / min and mix for 20 min. Then add the pretreated resin matrix, adjust the speed to 600 r / min, and mix for 40 min to form a stable composite powder system.

[0047] S3. Add 15 parts of modified polyethylene terephthalate short fibers to the above composite powder system, add 3 parts of silane coupling agent KH550, heat to 90℃, stir at 500 r / min, and mix for 35 min; then add 5 parts of foaming agent to the mixture, adjust the temperature to 80℃, stir at 400 r / min, and stir for 20 min to obtain the foaming precursor material;

[0048] S4. Preheat the mold to 110℃ and adjust the mold pressure to 8MPa, then keep it warm for later use. Preheat the mold with the above-mentioned foaming precursor material, and lay it out with a thickness of 1.5 times the target finished product thickness. Then lay the electromagnetic shielding nonwoven fabric on the upper and lower surfaces of the material, close the mold, and maintain a pressure of 8MPa for hot pressing and fusion. Maintain 110℃ and 8MPa pressure for 30 minutes to ensure that the foaming is completely bonded to the interface. After slowly depressurizing to normal pressure, continue to keep it warm for 15 minutes to eliminate internal stress and avoid deformation of the finished product.

[0049] S5. Remove the molded composite material and cure it again in a 130℃ forced-air drying oven for 3 hours. After naturally cooling to room temperature, trim and trim the edges according to the target installation area to obtain the automotive iron-nickel-based electromagnetic shielding material.

[0050] Example 3: Preparation of automotive iron-nickel-based electromagnetic shielding material. The specific preparation steps are as follows:

[0051] S1. Add 50 parts of polyurethane resin to the reactor, heat to 65°C, stir at 350 r / min, and keep warm and melt for 30 min to make the resin form a uniform flow state; add 0.5 parts of 2,6-di-tert-butyl-p-cresol and 1 part of sodium polycarboxylate, and continue stirring for 17 min to obtain the pretreated resin matrix.

[0052] S2. Add 40 parts of modified iron-nickel-based alloy powder, 5 parts of nano zinc oxide, and 6 parts of flax fiber to a high-speed mixer at a speed of 900 r / min for 17 min; then add the pretreated resin matrix, adjust the speed to 550 r / min, and mix for 35 min to form a stable composite powder system.

[0053] S3. Add 10 parts of modified polyethylene terephthalate short fibers to the above composite powder system, add 2 parts of silane coupling agent KH550, heat to 85℃, stir at 450 r / min, and mix for 30 min; then add 3 parts of foaming agent to the mixture, adjust the temperature to 75℃, stir at 350 r / min, and stir for 17 min to obtain the foaming precursor material;

[0054] S4. Preheat the mold to 105℃ and adjust the mold pressure to 6MPa, then keep it warm for later use. Preheat the mold with the above foaming precursor material, and lay it out with a thickness of 1.3 times the target finished product thickness. Then lay the electromagnetic shielding nonwoven fabric on the upper and lower surfaces of the material, and after closing the mold, maintain a pressure of 6MPa for hot pressing and fusion. Maintain 105℃ and 6MPa pressure for 25 minutes to ensure that the foaming is completely bonded to the interface. After slowly depressurizing to normal pressure, continue to keep it warm for 12 minutes to eliminate internal stress and avoid deformation of the finished product.

[0055] S5. Remove the molded composite material and cure it again in a 125℃ forced-air drying oven for 2.5 hours. After naturally cooling to room temperature, trim and trim the edges according to the target installation area to obtain the automotive iron-nickel-based electromagnetic shielding material.

[0056] Example 4: Preparation of modified iron-nickel based alloy powder. The specific preparation steps are as follows:

[0057] A1. Take 100g of iron-nickel-based alloy powder, add 400ml of deionized water, stir to disperse and form a suspension, adjust the pH to 5 with 1mol / L dilute hydrochloric acid; slowly add 20ml of tetrabutyl titanate, and simultaneously add 100ml of ethanol, and stir at 50℃ for 2h; continue to add 3g of silane coupling agent KH550 to the system, raise the temperature to 70℃, and stir to react for 1.5h; after the reaction is completed, filter and wash until neutral, and dry at 100℃ for 5h to obtain the first modified iron-nickel-based alloy powder;

[0058] A2. Take 100g of the first modified iron-nickel-based alloy powder, add 200ml of carboxylated multi-walled carbon nanotube aqueous dispersion, and ultrasonically disperse for 40min; prepare 50ml of iron-nickel chloride mixed solution, slowly add it dropwise to the above system, heat to 80℃, add 4g of citric acid as a complexing agent, stir for 10min, and then add 1mol / L sodium hydroxide solution to adjust the pH to 8; transfer the mixed system to a hydrothermal reactor and crystallize at 110℃ for 1.5h; after cooling to room temperature, magnetically agglomerate it for 10min under the action of an electromagnet with a magnetic field strength ≥0.8T, then decan the supernatant, collect the magnetic agglomeration product, wash it with deionized water until the filtrate is neutral, and vacuum dry at 100℃ for 4h to obtain the second modified iron-nickel-based alloy powder;

[0059] A3. Take 100g of the second modified iron-nickel-based alloy powder, add 300ml of N,N-dimethylformamide, and ultrasonically disperse for 30min; add 7ml of silane coupling agent KH570, heat to 70℃, and stir under nitrogen protection for 1.5h; then add 12ml of glycidyl methacrylate and 0.7g of benzoyl peroxide, heat to 85℃ and react for 2.5h; centrifuge to separate the product, wash 3 times with anhydrous ethanol to remove unreacted monomers and initiator residues, and dry at 130℃ for 5h to obtain the modified iron-nickel-based alloy powder.

[0060] Example 5: Preparation of modified iron-nickel based alloy powder. The specific preparation steps are as follows:

[0061] A1. Take 100g of iron-nickel-based alloy powder, add 500ml of deionized water, stir to disperse and form a suspension, adjust the pH value to 6 with 1mol / L dilute hydrochloric acid; slowly add 30ml of tetrabutyl titanate, and simultaneously add 150ml of ethanol, and stir at 60℃ for 3h; continue to add 5g of silane coupling agent KH550 to the system, raise the temperature to 80℃, and stir to react for 2h; after the reaction is completed, filter and wash until neutral, and dry at 100℃ for 5h to obtain the first modified iron-nickel-based alloy powder;

[0062] A2. Take 100g of the first modified iron-nickel-based alloy powder, add 300ml of carboxylated multi-walled carbon nanotube aqueous dispersion, and ultrasonically disperse for 40min; prepare 70ml of iron-nickel chloride mixed solution, slowly add it dropwise to the above system, heat to 90℃, add 6g of citric acid as a complexing agent, stir for 10min, and then add 1mol / L sodium hydroxide solution to adjust the pH to 9; transfer the mixed system to a hydrothermal reactor and crystallize at 120℃ for 2.5h; after cooling to room temperature, magnetically agglomerate it for 10min under the action of an electromagnet with a magnetic field strength ≥0.8T, then decan the supernatant, collect the magnetic agglomeration product, wash it with deionized water until the filtrate is neutral, and vacuum dry at 100℃ for 4h to obtain the second modified iron-nickel-based alloy powder;

[0063] A3. Take 100g of the second modified iron-nickel-based alloy powder, add 400ml of N,N-dimethylformamide, and ultrasonically disperse for 30min; add 9ml of silane coupling agent KH570, heat to 80℃, and stir for 2h under nitrogen protection; then add 16ml of glycidyl methacrylate and 0.9g of benzoyl peroxide, heat to 90℃ and react for 3h; centrifuge to separate the product, wash 3 times with anhydrous ethanol to remove unreacted monomers and initiator residues, and dry at 130℃ for 5h to obtain the modified iron-nickel-based alloy powder.

[0064] Example 6: Preparation of modified polyethylene terephthalate short fibers. The specific preparation steps are as follows:

[0065] B1. Take 100g of polyethylene terephthalate short fibers, add 500ml of 5wt.% sodium hydroxide solution, and stir at 80℃ for 2h; wash repeatedly with deionized water until the pH of the washing solution is 7, add 10ml of 1.5mol / L hydrochloric acid solution, and soak at room temperature for 30min; wash the product until neutral, and dry at 100℃ for 4h to obtain the first modified polyethylene terephthalate short fibers;

[0066] B2. Take 100g of the first-modified polyethylene terephthalate short fiber, add 300ml of deionized water, ultrasonically disperse for 20min, adjust the pH value to 4 with 0.2mol / L acetate-sodium acetate buffer solution; slowly add 8ml of silane coupling agent KH550, and simultaneously add 60ml of ethanol, stir and react at 60℃ for 1.5h; after the reaction is completed, filter, wash with water, and dry at 80℃ for 2h to obtain the second-modified polyethylene terephthalate short fiber;

[0067] B3. Take 100g of the second modified polyethylene terephthalate short fiber, add 200ml of 0.5mol / L hydrochloric acid solution, and soak for 30min; slowly add 10ml of aniline monomer, stir and adsorb at room temperature for 1h, then add 50ml of 1.2mol / L ammonium persulfate solution, and stir and react at 10℃ for 2h; after the reaction, filter and wash with water until no chloride ion residue remains; add the product to a pre-prepared 200ml dopamine solution (dopamine hydrochloride concentration 5g / L, solvent is pH 8.0 Tris-HCl buffer), heat to 40℃ and stir and react for 1h; after the reaction, filter and wash with water, and vacuum dry the product at 80℃ for 5h to obtain the modified polyethylene terephthalate short fiber.

[0068] Example 7: Preparation of modified polyethylene terephthalate short fibers. The specific preparation steps are as follows:

[0069] B1. Take 100g of polyethylene terephthalate short fibers, add 600ml of 5wt.% sodium hydroxide solution, and stir at 90℃ for 3h; wash repeatedly with deionized water until the pH of the washing solution is 7, add 15ml of 1.5mol / L hydrochloric acid solution, and soak at room temperature for 30min; wash the product until neutral, and dry at 100℃ for 4h to obtain the first modified polyethylene terephthalate short fibers;

[0070] B2. Take 100g of the first-modified polyethylene terephthalate short fiber, add 400ml of deionized water, ultrasonically disperse for 20min, adjust the pH value to 5 with 0.2mol / L acetate-sodium acetate buffer solution; slowly add 12ml of silane coupling agent KH550, and simultaneously add 70ml of ethanol, stir and react at 70℃ for 2h; after the reaction is completed, filter, wash with water, and dry at 80℃ for 2h to obtain the second-modified polyethylene terephthalate short fiber;

[0071] B3. Take 100g of the second modified polyethylene terephthalate short fiber, add 300ml of 0.5mol / L hydrochloric acid solution, and soak for 30min; slowly add 15ml of aniline monomer, stir and adsorb at room temperature for 1h, then add 70ml of 1.2mol / L ammonium persulfate solution, and stir and react at 15℃ for 3h; after the reaction, filter and wash with water until no chloride ion residue remains; add the product to a pre-prepared 300ml dopamine solution (dopamine hydrochloride concentration 5g / L, solvent is pH 8.0 Tris-HCl buffer), heat to 50℃ and stir and react for 1.5h; after the reaction, filter and wash with water, and vacuum dry the product at 80℃ for 5h to obtain the modified polyethylene terephthalate short fiber.

[0072] Comparative Example 1: Preparation of an iron-nickel-based electromagnetic shielding material for automobiles. The specific preparation steps are as follows:

[0073] The remaining steps remain unchanged, except that the modified iron-nickel-based alloy powder prepared in Example 4 and used in Example 3 are replaced with unmodified iron-nickel-based alloy powder to prepare an automotive iron-nickel-based electromagnetic shielding material.

[0074] Comparative Example 2: Preparation of automotive iron-nickel-based electromagnetic shielding material. The specific preparation steps are as follows:

[0075] The remaining steps remain unchanged, except that the modified polyethylene terephthalate short fibers prepared in Example 7 and used in Example 3 are replaced with unmodified polyethylene terephthalate short fibers to prepare an automotive iron-nickel-based electromagnetic shielding material.

[0076] Comparative Example 3: Preparation of automotive iron-nickel-based electromagnetic shielding material. The specific preparation steps are as follows:

[0077] The remaining steps remain unchanged, except that the modified iron-nickel-based alloy powder prepared in Example 4 used in Example 3 is replaced with unmodified iron-nickel-based alloy powder, and the modified polyethylene terephthalate short fiber prepared in Example 7 is replaced with unmodified polyethylene terephthalate short fiber, thus preparing an automotive iron-nickel-based electromagnetic shielding material.

[0078] Performance testing

[0079] Test Project Test Standards Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Electromagnetic shielding effectiveness (low frequency band 30kHz-1GHz) GB / T 25471-2010 65dB 72dB 78dB 50dB 62dB 40dB Electromagnetic shielding effectiveness (mid-to-high frequency band 1GHz-18GHz) GB / T 25471-2010 72dB 79dB 86dB 60dB 75dB 48dB Surface resistivity (Ω / sq) / <![CDATA[3.2×10 3 ]]> <![CDATA[2.1×10 3 ]]> <![CDATA[1.5×10 3 ]]> <![CDATA[8.7×10 4 ]]> <![CDATA[5.3×10 4 ]]> <![CDATA[1.2×10 5 ]]>

[0080] According to the performance test results, the automotive iron-nickel-based electromagnetic shielding materials prepared in Examples 1-3 are significantly superior to those in Comparative Examples 1-3 in terms of electromagnetic shielding effectiveness and surface resistivity: In the low-frequency band (30kHz-1GHz), the shielding effectiveness of the examples is 65-78dB, while that of the comparative examples is only 40-62dB; in the mid-to-high frequency band (1GHz-18GHz), the shielding effectiveness of the examples reaches 72-86dB, while that of the comparative examples is 48-75dB; in terms of surface resistivity, the examples are 1.5×10⁻⁶. 3-3.2×10 3 Ω / sq, with a comparative ratio as high as 5.3×10 4 -1.2×10 5 The performance of Example 3 was the best, with Ω / sq, indicating that the synergistic effect of modified iron-nickel based alloy powder and modified polyethylene terephthalate short fiber can effectively improve the electromagnetic shielding performance and conductivity of the material.

[0081] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A nickel-iron-based electromagnetic shielding material for automobiles, characterized in that: It contains the following raw materials by weight: 30-50 parts modified iron-nickel based alloy powder, 40-60 parts polyurethane resin, 5-15 parts modified polyethylene terephthalate short fiber, 2-8 parts nano zinc oxide, 3-10 parts flax fiber, 1-3 parts silane coupling agent KH550, 2-5 parts foaming agent, 0.3-0.8 parts 2,6-di-tert-butyl-p-cresol, 0.5-2 parts sodium polycarboxylate, and sufficient electromagnetic shielding nonwoven fabric.

2. The automotive iron-nickel-based electromagnetic shielding material according to claim 1, characterized in that: The flax fiber was treated with alkali, specifically by taking 100g of flax fiber, adding it to 500ml of 5wt.% sodium hydroxide solution, stirring at 80℃ for 2h, washing until neutral, and then drying at 100℃ for 3h.

3. The automotive iron-nickel-based electromagnetic shielding material according to claim 1, characterized in that: The electromagnetic shielding nonwoven fabric has a silver fiber content of ≥15% and a surface density of 80-120 g / m³. 2 .

4. The automotive iron-nickel-based electromagnetic shielding material according to claim 1, characterized in that: The foaming agent is a compound of sodium bicarbonate and citric acid in a mass ratio of 1.3:

1.

5. The automotive iron-nickel-based electromagnetic shielding material according to claim 1, characterized in that: The modified iron-nickel-based alloy powder is prepared using the following specific steps: A1. Take iron-nickel-based alloy powder, add deionized water, stir to disperse and form a suspension, adjust the pH value to 5-6 with 1mol / L dilute hydrochloric acid; slowly add tetrabutyl titanate, and simultaneously add ethanol, and stir at 50-60℃ for 2-3 hours; continue to add silane coupling agent KH550 to the system, raise the temperature to 70-80℃, and stir the reaction for 1.5-2 hours; after the reaction is completed, filter and wash until neutral, and dry at 100℃ for 5 hours to obtain the first modified iron-nickel-based alloy powder; A2. Take the first modified iron-nickel-based alloy powder, add carboxylated multi-walled carbon nanotube aqueous dispersion, and ultrasonically disperse for 40 min; prepare iron-nickel chloride mixed solution, slowly add it dropwise to the above system, heat to 80-90℃, add citric acid as a complexing agent, stir for 10 min, and then add 1 mol / L sodium hydroxide solution to adjust the pH to 8-9; transfer the mixed system to a hydrothermal reactor and crystallize at 110-120℃ for 1.5-2.5 h; after cooling to room temperature, magnetically agglomerate it for 10 min under the action of an electromagnet with a magnetic field strength ≥0.8T, then decant the supernatant, collect the magnetic agglomeration product, wash it with deionized water until the filtrate is neutral, and vacuum dry at 100℃ for 4 h to obtain the second modified iron-nickel-based alloy powder; A3. Take the second modified iron-nickel-based alloy powder, add N,N-dimethylformamide, and ultrasonically disperse for 30 min; add silane coupling agent KH570, heat to 70-80℃, and stir under nitrogen protection for 1.5-2 h; then add glycidyl methacrylate and benzoyl peroxide, heat to 85-90℃, and react for 2.5-3 h. The product was centrifuged and washed three times with anhydrous ethanol to remove unreacted monomers and initiator residues. It was then dried at 130°C for 5 hours to obtain modified iron-nickel-based alloy powder.

6. The automotive iron-nickel-based electromagnetic shielding material according to claim 5, characterized in that: The ratio of iron-nickel-based alloy powder, deionized water, tetrabutyl titanate, ethanol, and silane coupling agent KH550 in A1 is 100g: 400-500ml: 20-30ml: 100-150ml: 3-5g; the iron-nickel-based alloy powder has a nickel content of 70-80%, an iron content of 20-30%, and a particle size of 5-20μm. The ratio of the first modified iron-nickel-based alloy powder, carboxylated multi-walled carbon nanotube aqueous dispersion, iron-nickel chloride mixed solution, and citric acid in A2 is 100g:200-300ml:50-70ml:4-6g; wherein the carboxylated multi-walled carbon nanotube aqueous dispersion has a solid content of 1.5wt.% and a pH of 3-4; the iron-nickel chloride mixed solution is FeCl₂. 3• 6H2O and NiCl 2• Mixed with 6H2O, in which Fe 3+ :Ni 2+ Molar ratio 2:1, total concentration 0.8 mol / L; The ratio of the second modified iron-nickel-based alloy powder, N,N-dimethylformamide, silane coupling agent KH570, glycidyl methacrylate, and benzoyl peroxide in A3 is 100g:300-400ml:7-9ml:12-16ml:0.7-0.9g.

7. The automotive iron-nickel-based electromagnetic shielding material according to claim 1, characterized in that: The modified polyethylene terephthalate short fibers are prepared using the following specific steps: B1. Take polyethylene terephthalate short fibers, add 5 wt.% sodium hydroxide solution, and stir at 80-90℃ for 2-3 hours; wash repeatedly with deionized water until the pH of the washing solution is 7, add 1.5 mol / L hydrochloric acid solution, and soak at room temperature for 30 minutes; wash the product until neutral, and dry at 100℃ for 4 hours to obtain the first modified polyethylene terephthalate short fibers; B2. Take the first modified polyethylene terephthalate short fibers, add deionized water, and ultrasonically disperse for 20 min. Adjust the pH value to 4-5 with a 0.2 mol / L acetate-sodium acetate buffer solution. Slowly add silane coupling agent KH550 and ethanol at the same time. Stir and react at 60-70℃ for 1.5-2 h. After the reaction is completed, filter and wash with water, and dry at 80℃ for 2 h to obtain the second modified polyethylene terephthalate short fibers. B3. Take the second modified polyethylene terephthalate short fibers, add 0.5 mol / L hydrochloric acid solution, and soak for 30 min; slowly add aniline monomer, stir and adsorb at room temperature for 1 h, then add 1.2 mol / L ammonium persulfate solution, stir and react at 10-15℃ for 2-3 h; after completion, filter and wash with water until no chloride ion residue remains; The product was added to a pre-prepared dopamine solution, heated to 40-50℃ and stirred for 1-1.5 hours. After the reaction was completed, the product was filtered, washed with water, and dried under vacuum at 80℃ for 5 hours to obtain modified polyethylene terephthalate short fibers.

8. The automotive iron-nickel-based electromagnetic shielding material according to claim 7, characterized in that: The ratio of polyethylene terephthalate short fibers, sodium hydroxide solution, and hydrochloric acid solution in B1 is 100g: 500-600ml: 10-15ml; The ratio of the first modified polyethylene terephthalate short fiber, deionized water, silane coupling agent KH550, and ethanol in B2 is 100g: 300-400ml: 8-12ml: 60-70ml. The ratio of the second modified polyethylene terephthalate short fibers, hydrochloric acid solution, aniline monomer, ammonium persulfate solution, and dopamine solution in B3 is 100g: 200-300ml: 10-15ml: 50-70ml: 200-300ml; the dopamine solution contains 5g / L dopamine hydrochloride and is in Tris-HCl buffer solution at pH 8.

0.

9. A method for preparing an automotive iron-nickel-based electromagnetic shielding material, characterized in that: Specifically, it includes the following steps: S1. Add 40-60 parts of polyurethane resin to the reactor, heat to 60-70℃, stir at 300-400 r / min, and keep warm for 30 min to melt the resin and make it form a uniform flow state; add 0.3-0.8 parts of 2,6-di-tert-butyl-p-cresol and 0.5-2 parts of sodium polycarboxylate, and continue stirring for 15-20 min to obtain the pretreated resin matrix; S2. Add 30-50 parts of modified iron-nickel-based alloy powder, 2-8 parts of nano zinc oxide, and 3-10 parts of flax fiber to a high-speed mixer at a speed of 800-1000 r / min and mix for 15-20 min. Then add the pretreated resin matrix, adjust the rotation speed to 500-600 r / min, mix for 30-40 min, and form a stable composite powder system; S3. Add 5-15 parts of modified polyethylene terephthalate short fibers to the above composite powder system, add 1-3 parts of silane coupling agent KH550, heat to 80-90℃, stir at 400-500 r / min, and mix for 25-35 min; then add 2-5 parts of foaming agent to the mixture, adjust the temperature to 70-80℃, stir at 300-400 r / min, and stir for 15-20 min to obtain the foaming precursor material; S4. Preheat the mold to 100-110℃ and adjust the mold pressure to 5-8MPa, then keep it warm for later use. Preheat the mold with the above-mentioned foaming precursor material, and lay it out with a thickness of 1.2-1.5 times the target finished product thickness. Then, lay the electromagnetic shielding non-woven fabric on the upper and lower surfaces of the material, and after closing the mold, maintain a pressure of 5-8MPa for hot pressing and fusion. Maintain 100-110℃ and 5-8MPa pressure for 20-30 minutes to ensure that the foaming is completely bonded to the interface. After slowly depressurizing to normal pressure, continue to keep it warm for 10-15 minutes to eliminate internal stress and avoid deformation of the finished product. S5. Remove the molded composite material and cure it again in a 120-130℃ forced-air drying oven for 2-3 hours. After naturally cooling to room temperature, trim and trim the edges according to the dimensions of the target installation part to obtain the automotive iron-nickel-based electromagnetic shielding material.